1. Field of the Invention
The present invention relates to a reciprocating compressor and, more particularly, to a reciprocating compressor with an improved suction structure of a refrigerant gas that is capable of minimizing a suction loss due to suction overheating caused during operation.
2. Description of the Background Art
In general, a compressor constituting a refrigerating cycle unit compresses a refrigerant gas in a low temperature and low pressure state introduced from an evaporator and discharges a high temperature and high pressure refrigerant gas.
Compressors can be classified as a rotary compressor, a reciprocating compressor, a scroll compressor, or the like, according to a fluid compression method.
Particularly, the reciprocating compressor, which compresses and takes-in a fluid as a piston moves linearly, is generally divided into those that operate by a method in which a fluid is taken-in and compressed by switching or converting a rotational movement of a driving motor into a reciprocal movement of the piston, and those that operate by a method in which a fluid is taken-in and compressed by allowing the piston to make a reciprocal movement while the driving motor moves linearly and reciprocally.
FIG. 1 is a vertical-sectional view showing the inside of a conventional reciprocating compressor.
As depicted, the conventional reciprocating compressor includes a case 10 having a gas suction pipe (SP) and a gas discharge pipe (DP), a frame unit 20 having a front frame 21 and a rear frame 22 respectively installed at a front side and a rear side in the case 10 and a middle frame 23 installed at the middle portion between the front and rear frames 21 and 22. A reciprocating motor 30 is installed between the middle frame 23 and the rear frame 22 and generates a driving force, a compression unit 70 having a cylinder 40 is installed at the center of the front frame 21, and a piston 50 is linearly and reciprocally moved into the cylinder 40 by virtue of the driving force of the reciprocating motor 30. A discharge cover 61 is installed at the front side of the cylinder 40 and forms a compression chamber (P) therein, a discharge valve 62 is positioned inside the discharge cover 61 and selectively opens and closes the compression chamber (P), a valve spring 63 elastically supports the discharge valve 62, and a suction valve 64 coupled at the front surface of the piston 50 selectively opens and closes a gas suction passage (F) formed inside the piston 50. A spring unit 80 is installed between the front frame 20 and the middle frame 23 and provides an elastic force to the piston 50.
The reciprocating motor 30 includes an outer stator 31 fixed between the middle frame 23 and the rear frame 22, an inner stator 32 inserted into the outer stator 31 with a space therebetween, and a mover 34 reciprocally installed between the outer stator 31 and the inner stator 32 and connected to the piston 50.
In the conventional reciprocating compressor, the gas suction pipe (SP) is installed at the side of the rear frame 22 and a gas discharge pipe (DP) is installed at the side of the front frame 21. A suction muffler (M) is installed at the side of the rear frame 22 in order to cancel a suction noise generated during operation of the reciprocating compressor.
The operation of the reciprocating compressor constructed as described above will now be explained.
When power is supplied to the reciprocating motor 30, the mover 34 is linearly and reciprocally moved by virtue of a magnetic flux formed at the outer stator 31 and the inner stator 32.
At this time, the piston 50 connected to the mover 34 is linearly and reciprocally moved into a through hole. 41 of the cylinder 40.
At the same time, gas is introduced through the gas suction pipe (SP) of the case 10, and the introduced gas is taken into the compression chamber (P) according to the operation of the compression unit 70 and then discharged through the gas discharge pipe (DP).
However, in the conventional reciprocating compressor, after the refrigerant gas introduced into the gas suction pipe (SP) passes the reciprocating motor 30, it is taken into the compression chamber (P) through the suction passage (F) of the piston 50 and discharged into the discharge pipe (DP). In this process, however, a suction loss occurs due to generation of heat by the reciprocating motor 30. Such a suction loss due to the suction overheating of the reciprocating motor 30 causes a degradation in performance of the compressor.
In addition, in the conventional reciprocating compressor, the suction muffler (M) is installed at the rear frame 22 in order to minimize or remove a suction noise generated during operation. However, since the suction noise generated due to the reciprocal movement of the piston 50 is directly transmitted outside the compressor through the gas suction pipe (DP), not only the muffling effect is degraded but also the overall length (or height) of the compressor is increased due to such location of the suction muffler.